Auto body conveyor apparatus has been known for many years, and a typical such apparatus is disclosed in U.S. Pat. No. 3,926,125 to Orwin, and has an auto body supporting frame 19 which is moved along a conveyor beam means 10 on a trolley 15. The hanger frame has spaced pairs of hanger arms depending therefrom on opposite sides of the hanger frame, and these are pivotable outwardly from the line along which the auto body 20 is conveyed.
A typical means for supporting the auto body on such a conveyor apparatus is shown in U.S. Pat. No. 4,464,998 to Wakabayashi, and consists of inwardly extending article support members 29 on which the lower edges of the auto body rest. As will be understood, because the lower edges of the auto body simply rest on the flat surfaces, there is nothing which precisely positions the auto body on the article support members 29, and the auto body is free to shift under forces which are exerted on it during the conveyance thereof along the conveyor apparatus.
This problem has been recognized, and Published Japanese Application No. 59-27979 of Feb. 21, 1984, proposes a solution to this problem. In this publication, there is provided article support members 19 each of which have a series of V-shaped notches 25 spaced inwardly from the lower end of the hanger arm 17, 18 and the side sill 27 along the bottom edge of the auto body 26 engages in the V-shaped notches in the hangers on the opposite sides of the line along which the conveyor apparatus moves, thus holding the auto body against lateral movement transverse to the line of the conveyor.
However, while this construction provides some improvement in the positioning of the auto body, because the hanger arms and the hanger frames tend to be distorted slightly because of stresses exerted on them during normal use, the position of the support members 19 can change slightly, and also the dimension between the side sills on the opposite sides of the auto body can change slightly from auto body to auto body. This will result in the side sill on one side of the body engaging in the bottom of a V-shaped notch, while the sill on the other side may ride up the side of the V of the notch somewhat. This tends to tilt the body somewhat, and also it does not always occur on the same side of the body, so that one body may be shifted slightly to one side of the conveyor line and the next body might be shifted to the opposite side.
For many purposes, this lack of precision in the position of the auto body is not significant, but where robots are employed to perform operations on the auto body, such lack of precision in the positioning of the auto body makes the positioning and functioning of the robots so that they engage the auto body in the proper position extremely difficult.